Obesity is a disease of excess, but a new study suggests that a few obese patients are actually lacking something-a piece of one of their chromosomes. The loss might remove a gene that helps the body manage blood sugar and appetite. If you watch enough television, you'll witness what psychologists describe as birth order stereotypes. Take Alex P. Keaton of the 1980s U.S. sitcom Family Ties. Firstborn Alex was far more brash and competitive than his younger sisters, reading The Wall Street Journal while in high school, for example. Now scientists report that the stereotype is valid: Eldest children are less cooperative, trusting, and reciprocating than their siblings.
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